A binary image sensor may comprise e.g. more than 109 individual light detectors arranged as a two-dimensional array. Each individual light detector has only two possible states: an unexposed “black” state and an exposed “white” state. Thus, an individual detector does not reproduce different shades of grey. The local brightness of an image may be determined e.g. by the local spatial density of white pixels.
The size of the individual light detectors of a binary image sensor may be smaller than the minimum size of a focal spot which can be provided by the imaging optics of a digital camera. The use of such detectors may help to avoid e.g. color aliasing problems due to color filter arrays.
However, storing or transferring binary digital images as such may be difficult or impossible due to the large data size. Several exposures and read-outs may be needed to attain a sufficient signal-to-noise ratio. The resulting image data may even be so large that storing and processing of the binary digital images becomes impractical in a digital camera, or even in a desktop computer.